Document Detail


Assessing direction-specific adaptation using the steady-state visual evoked potential: results from EEG source imaging.
MedLine Citation:
PMID:  19761323     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Studying directional selectivity using neuroimaging in humans is difficult because the resolution is insufficient to directly access directionally selective activity. Here we used motion adaptation of the steady-state visual evoked potential (SSVEP) and source imaging in the frequency domain to detect brain areas that contain direction-selective cells. This study uses a definitive electrophysiological marker for direction-specific adaptation in the SSVEP to localize cortical areas that are direction selective. It has been shown previously that an oscillating stimulus produces an SSVEP response that is dominated by even harmonics of the stimulus frequency. This pattern of response is consistent with equal population responses to each direction of motion. Prolonged exposure to unidirectional motion induces an asymmetry in the population response that is consistent with adaptation of direction-selective cells. This asymmetry manifests itself in the presence of odd harmonic components after adaptation Critically, the feature that indicates the direction used for adaptation is the phase of the odd-harmonic responses. We recorded this signature of direction selectivity in a group of observers whose retinotopic visual areas had been defined from fMRI mapping. We find direction-specific responses throughout retinotopic cortex, with the largest effect in areas V1 (occipital pole) and V3/V3a (dorsal).
Authors:
Justin M Ales; Anthony M Norcia
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Publication Detail:
Type:  Journal Article     Date:  2009-07-14
Journal Detail:
Title:  Journal of vision     Volume:  9     ISSN:  1534-7362     ISO Abbreviation:  J Vis     Publication Date:  2009  
Date Detail:
Created Date:  2009-09-18     Completed Date:  2009-12-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101147197     Medline TA:  J Vis     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8     Citation Subset:  IM    
Affiliation:
Smith-Kettlewell Eye Research Institute, San Francisco, CA 94115, USA. ales@ski.org
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological*
Adult
Brain Mapping
Electroencephalography*
Evoked Potentials, Visual*
Female
Homeostasis*
Humans
Magnetic Resonance Imaging
Male
Models, Neurological
Motion Perception / physiology*
Occipital Lobe / anatomy & histology,  physiology
Orientation / physiology
Retina / physiology
Visual Cortex / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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